1. Field of the Invention
The present invention relates to a controller for an industrial machine provided with an electric motor, such as a machine tool, a robot, etc.
2. Description of the Related Art
In a system including an industrial machine, such as a machine tool or a robot, provided with a mechanical part driven by an electric motor using electric power, information on the electric power consumption of the industrial machine is often required for various purposes. The information on the electric power consumption can be obtained by a wattmeter attached to an electric power source of the industrial machine.
Japanese Unexamined Patent Publication (Kokai) No. 2000-206150 (JP2000-206150A) describes a configuration in which a controller of an industrial machine determines electric power consumption by calculation. In this configuration, the controller determines the electric power consumption of an electric motor based on a feedback signal of a motor current detection value that is in turn used for controlling the electric motor in order to operate the mechanical part of the industrial machine to perform a desired motion. Further, since a power consuming component other than the electric motor (i.e., a peripheral apparatus), such as a heater provided in the industrial machine, consumes constant electric power during the operation thereof, the controller also determines the electric power consumption of the peripheral apparatus by using data of the operating time thereof, which can be obtained in the controller. Thus, the information on the electric power consumption for each of the various power consuming components is determined by calculation, so as to be usable for analysis for, e.g., the effective utilization of electric power.
Thus, information on the electric power consumption of the industrial machine may generally be obtained by using a wattmeter, while the controller of the industrial machine can calculate electric power consumption based on data used for performing an operational control. The configuration wherein the controller calculates the electric power consumption by using the data for operational control is rational, and thus can eliminate the need of a dedicated device, such as a wattmeter, and reduce cost. Further, the configuration wherein the controller determines the electric power consumption, makes it possible to perform electricity consumption analysis based on the electric power consumption of each of a plurality of electric motors.